Continuous Phase Modulation for Multi-Level Spreading Codes in CDMA Communications

Continuous phase modulation has been favorably considered for use in DS-CDMA communications due to its constant envelope and spectral efficiency over other competing signaling techniques. On the other hand, more recently proposed multi-level orthogonal spreading code families offer better inter- and intra-code correlation properties than the conventional binary code families like Gold and Walsh. This paper evaluates BER performance of a system employing CPM technique for signaling and multi-level orthogonal spreading codes for DS-CDMA communications. It is shown that CPM-DS-CDMA system employing multi-level spreading codes significantly outperform binary spreading codes under the same test conditions.